Can you measure a PR interval for PVCs?

• A. You can measure it Before the PVC Occurs
• B. You can measure it After the PVC Resolves
• C. You Cannot Measure It During the PVC, But You Can Measure It Before the PVC Occurs
• D. You Can Measure It During the PVC

Answer: (C)

The PR interval tracks the time from the start of atrial depolarization (the P wave) to the start of ventricular depolarization (the QRS) for a beat that is actually conducted through the normal atrioventricular pathway. A PVC comes from a ventricular origin, so that beat is not driven by the standard atrial-to-ventricular conduction system and typically has no preceding P wave. Because of that, the PR interval for the PVC itself isn’t defined or measurable.

You can, however, measure the PR interval for the beat that occurs before the PVC (a normal conducted beat) and for the beat that follows after the PVC resolves if it is conducted normally. In short: the PR interval cannot be measured during the PVC, but it can be measured for the preceding (and following) normal beats.